Reportable Business Segments (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues		$ 3,531	$ 3,155
Operating Income (Loss)		245	251
Equity in earnings from investment in Enable		62	69
Assets		33,902		$ 27,009
Goodwill		5,129		867
Total regulatory assets		2,265		2,044
Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	689	751
Operating Income (Loss)		84	115
Houston Electric T&D [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		151	161
Houston Electric T&D [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		54	54
Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Revenues		83	0
Operating Income (Loss)		(9)	0
Goodwill		0		0
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		1,389	1,143
Operating Income (Loss)		167	156
Goodwill		746		746
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		1,182	1,257
Operating Income (Loss)		33	(26)
Goodwill	[2]	110		110
Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues		146	0
Operating Income (Loss)		(16)	0
Goodwill		6		0
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[3]	0	0
Operating Income (Loss)	[3]	0	0
Equity in earnings from investment in Enable		62	69
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		42	4
Operating Income (Loss)		(14)	6
Goodwill		11		11
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(74)	(38)
Assets		(2,757)		(652)
Intersegment Eliminations [Member] | Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Revenues		0	0
Intersegment Eliminations [Member] | Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Revenues		0	0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(10)	(10)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(64)	(28)
Intersegment Eliminations [Member] | Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues		0	0
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[3]	0	0
Intersegment Eliminations [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		0	0
Operating Segments [Member] | Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Assets		11,420		10,509
Operating Segments [Member] | Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Assets	[4]	1,953		0
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets	[4]	10,492		6,956
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,370		1,558
Operating Segments [Member] | Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Assets	[4]	814		0
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		2,839		2,482
Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets	[4],[5]	3,515		6,156
Pension and Other Postretirement Plans Costs [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total regulatory assets		652		665
Houston Electric [Member]
Segment Reporting Information [Line Items]
Revenues		686	755
Operating Income (Loss)		81	119
Assets		11,420		10,507
Total regulatory assets		1,056		1,124
Houston Electric [Member] | Houston Electric T&D [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		151	161
Houston Electric [Member] | Houston Electric T&D [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		54	54
CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues		2,368	2,400
Operating Income (Loss)		196	131
Assets		8,065		8,214
Goodwill		867		867
Total regulatory assets		216		258
CERC Corp [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		1,185	1,143
Operating Income (Loss)		164	156
Goodwill		746		746
CERC Corp [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		1,182	1,257
Operating Income (Loss)		33	(26)
Goodwill	[6]	110		110
CERC Corp [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		1	0
Operating Income (Loss)		(1)	1
Goodwill		11		11
CERC Corp [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(74)	(38)
Assets		(289)		(366)
CERC Corp [Member] | Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(10)	(10)
CERC Corp [Member] | Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(64)	(28)
CERC Corp [Member] | Intersegment Eliminations [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		0	$ 0
CERC Corp [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,904		6,956
CERC Corp [Member] | Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,370		1,558
CERC Corp [Member] | Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets	[4]	80		66
Vectren [Member]
Segment Reporting Information [Line Items]
Revenues		473
Goodwill	[7]	$ 4,256		0
Cash and Cash Equivalents [Member]
Segment Reporting Information [Line Items]
Short-term Investments				$ 3,900

[1] Houston Electric T&D revenues from major customers are as follows: Three Months Ended March 31, 2019 2018 (in millions)Affiliates of NRG $151 $161Affiliates of Vistra Energy Corp. 54 54

[2] Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.

[3] CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended March 31, 2019 2018 (in millions)Enable $62 $69

[4] Total assets by reportable segment include assets acquired in the Merger, which are based on preliminary estimates and are subject to change. See Note 3.

[5] Includes pension and other postemployment-related regulatory assets of $652 million and $665 million, respectively, as of March 31, 2019 and December 31, 2018. Additionally, total assets as of December 31, 2018 included $3.9 billion of temporary investments included in Cash and cash equivalents on CenterPoint Energy’s Consolidated Balance Sheets.

[6] Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.

[7] CenterPoint Energy is currently assessing its reporting units subsequent to the Merger and the allocation of goodwill from the Merger to those reporting units. See Note 3.